MemPharos: Custom User-Space Memory Pagers

MemPharos is a collection of custom user-space memory pagers for ELF binaries on Linux systems. This project implements different memory paging strategies for loading and executing ELF binaries, providing insights into memory management and paging mechanisms.

Overview

This project demonstrates several implementations of memory pagers:

• APager: Basic ELF loader that maps segments into memory
• DPager: Demand paging implementation with SIGSEGV handling for lazy loading
• HPager: Hybrid paging approach

Each pager implements different strategies for memory allocation, stack setup, and execution of ELF binaries, showcasing various aspects of user-space memory management.

Test Programs

The repository includes several test programs to demonstrate the pagers in action:

• hello_world.c: Simple "Hello World" program
• adding_nums.c: Basic arithmetic operations
• null.c: NULL pointer handling
• data.c: Data manipulation example
• crazy_manipulation.c: More complex data manipulations
• longstring_longmath.c: String and mathematical operations
• extreme_page_faulting.c: Test case for page fault handling

Building and Running

Use the provided Makefile to build all pagers and test programs:

make

To run a test program with a specific pager:

./apager hello_world
./dpager adding_nums
./hpager data

Cleaning up

To clean up compiled binaries:

make clean

Technical Details

These pagers demonstrate various memory management techniques:

1. ELF Binary Loading: Parsing and loading ELF headers and program segments
2. Stack Management: Setting up the stack with proper alignment and layout for program execution
3. Signal Handling: Intercepting page faults for demand paging
4. Memory Mapping: Using mmap/munmap for segment allocation and deallocation

Requirements

• Linux operating system
• GCC compiler